linux-kernel - Re: [PATCH 07/11] kexec: Disable in a secure boot environment

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Date:	Tue, 04 Sep 2012 21:33:31 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Matthew Garrett <mjg59@...f.ucam.org>
Cc:	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org, linux-efi@...r.kernel.org
Subject: Re: [PATCH 07/11] kexec: Disable in a secure boot environment

Matthew Garrett <mjg59@...f.ucam.org> writes:

> On Tue, Sep 04, 2012 at 03:12:52PM -0700, Eric W. Biederman wrote:
>> Matthew Garrett <mjg59@...f.ucam.org> writes:
>> > The driving force behind this code right now is that our choices are 
>> > either (1) do something like this, or (2) disable kexec entirely.
>> 
>> Actually there is an interesting question here. Why does even EFI secure
>> boot justify this?  If I install my own key in EFI I should be able to
>> boot a kernel that does anything I want it to.   My machine doing what I
>> want it to is the point of trusted boot is it not?
>
> The full implementation should trust keys that are trusted by the 
> platform, so it'd boot any kexec image you cared to sign. Or simply 
> patch this code out and rebuild and self-sign, or disable the code that 
> turns off the capability when in secure boot mode. I've no objection to 
> putting that behind an #ifdef.

I will be happy to see a version of kexec that accepts signed images,
allowing the functionality to work in your brave new world where
everything must be signed.

Until then I don't see a point in merging anything else.

I will be happy to see some reasonable patchs for signing support on the
kexec path.

Eric
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